bpo-44342: [Enum] fix data type search (GH-26667)

In an inheritance chain of

  int -> my_int -> final_int

the data type is now final_int (not my_int)
(cherry picked from commit 3a7cccfd6cd3693e1a2ab65ee05d7f45f8501dfa)

Co-authored-by: Ethan Furman <ethan@stoneleaf.us>

Co-authored-by: Ethan Furman <ethan@stoneleaf.us>
diff --git a/Lib/test/test_enum.py b/Lib/test/test_enum.py
index ceb0da8..956b834 100644
--- a/Lib/test/test_enum.py
+++ b/Lib/test/test_enum.py
@@ -658,6 +658,14 @@ class MyEnum(HexInt, enum.Enum):
             def __repr__(self):
                 return '<%s.%s: %r>' % (self.__class__.__name__, self._name_, self._value_)
         self.assertEqual(repr(MyEnum.A), '<MyEnum.A: 0x1>')
+        #
+        class SillyInt(HexInt):
+            pass
+        class MyOtherEnum(SillyInt, enum.Enum):
+            D = 4
+            E = 5
+            F = 6
+        self.assertIs(MyOtherEnum._member_type_, SillyInt)
 
     def test_too_many_data_types(self):
         with self.assertRaisesRegex(TypeError, 'too many data types'):